?une 2&, 1888] 



NATURE 



207 



is, however, both interesting and important and should lead to 

 further inquiries in the same direction, when a more extended 

 series of observations should be laid under contribution. 



ASTRONOMICAL PHENOMENA FOR THE 

 WEEK 1888 JULY 1-7. 



/"pOR the reckoning of time the civil day, commencing at 

 * ■*■ Greenwich mean midnight, counting the hours on to 24, 

 is here employed. ) 



At Greenwich on July I 

 Sun rises, 3I1. 50m.; souths, I2h. 3m. 38 - 5s. ; sets, 2oh. 17m. : 



right asc. on meridian, 6h. 43'5tn. ; decl. 23 4' N. 



Sidereal Time at Sunset, 14b. 58m. 

 Moon (at Last Quarter July 1, 4I1.) rises, oh. 8m. ; souths, 



6h. 9m. ; sets, I2h. 22m. : right asc. on meridian, 



oh. 47*5m. ; decl. o° 16' S. 



GEOGRAPHICAL NOTES. 



At Monday's meeting of the Royal Geographical Society, Lieu- 

 tenant Wissmann was present, and was formally presented by the 

 President with the gold medal which has been awarded to him by 

 the Society f >r his exploring work in Africa. Lieutenant Wissmann 

 afterwards gave some account of his explorations in the region 

 to the south of the great Congo bend. He began his African 

 work eight years ago in company with the late Dr. Pogge, with 

 whom he traversed the region lying between Loanda and 

 Nyangwe on the Upper Congo. The Kassai and several others 

 of the great rivers that flow north to the Congo were crossed, 

 and a large area of new country, thickly covered with an 

 interesting population, opened up. Dr. Pogge returned to 

 the west coast, whilst Lieutenant Wissmann proceeded from 

 Nyangwe to Zanzibar. He returned to Africa a second time in 

 the service of the King of the Belgians, and in company with 



Dr. Wolf, Lieutenant von Francois, and others, made his way 

 again from Loanda into the interior. During the period between 

 1884 and 1887, Lieutenant Wissmann explored the Great Kassai, 

 and did much to unravel the complicated system of rivers, of which 

 it is the centre. Moreover, his observations on the people, as well 

 as the fauna and flora, render his work of great scientific value. 

 He again crossed to Nyangwe, and, by Lakes Tanganyika and 

 Nyassa, reached the east coast at the mouth of the Zambesi. He 

 returned to Europe in the autumn of last year, with his health 

 shattered, and was compelled to go to Madeira to recruit. Now 

 Lieutenant Wissmann returns to Germany, and will no doubt 

 there work out the results of his eight years' work in Africa. 

 Already one volume has been published, dealing with the 

 exploration of the Kassai- Sankuni. 



Captain W. J. L. Wharton, the Hydrographer, also read a 

 paper at Monday's meeting of the Royal Geographical Society. 

 He described the results of a very complete examination which 

 has recently been made of Christmas Island, in the Indian 

 Ocean, some 200 miles south of the western end of Java. The 

 island is a peculiar one, and extremely difficult to explore. It 

 consists apparently of high cliffs of coral, covered with the 

 densest vegetation. After describing the results of examination 

 by Captain Aldrich and others, Captain Wharton concluded by 

 giving a summary of the conclusions to be drawn. We have, 

 he said, a high island, on the surface of which, wherever ex- 

 amined, we findlimestone, bearing in most places the appearance 

 of coral origin, though in some specimens the shells of the 

 Foraminifera abound, and in none of them have direct evidences 

 of coral structure been detected. It must be remembered, how- 

 ever, that coral limestone becomes so altered by the deposition 

 of lime by infiltration, that a large surface of it may be 

 searched before a piece retaining its coralline structure is found, 

 and that the specimens sent home are very small. From the 

 description of Captain Aldrich, who is well acquainted with 

 coral formations, it may be taken for granted that the majority 

 of this rock is of coral origin. The rock forming the 

 summit is of this structureless character. In two spots, and 

 at the bottom of a hole in the summit of the ridge, we have 

 volcanic rock. The island is very steep on all sides, great 

 depths being found close to the cliffs, while on all sides, at a 

 short distance, soundings over three miles in depth were 

 obtained. It appears, then, most probable that Christmas 

 Island is founded on a volcanic mound which rose from the 

 bottom to a certain distance from the surface of the sea ; that 

 Foraminifera shells dying on the surface were rained upon it in 

 sufficient number to form a stratum, since solidified into lime- 

 stone rock ; that as the mound neared the surface, corals built 

 upon it, and it is possible from the sketch of the island, and 

 from Captain Aldrich's description of the slope of the ridge 

 inwards, that it first assumed an atoll form. This, however, is 

 a mere inference from probabilities. The island was next 

 gradually upheaved, the coral growing outwards on the gentle 

 slope until a period of immobility ensued long enough to permit 

 the waves to erode the upper cliff. Another short period of 

 upheaval, and one of stationary character ensued, when the 

 second cliff was worn away. A third interval of upheaval, 

 probably longer than the others, and then a second stand, when 

 the lowest and highest inland cliff was formed. Finally, another 

 lift was given, and the stationary period now in existence com- 

 pleted the process. The volcanic stones found in various places 

 on the higher parts of the island point to a thinning of the 

 limestone covering in those places. Denudation has worn away 

 the limestone, and the volcanic core is consequently exposed. Man 

 has never lived on Christmas Island, nor would it be a pleasant 

 residence, as, apart from the fact that there is no water — the 

 rain sinking into the limestone xoc\ — the extreme discomfort of 

 locomotion, and the absence of any harbour whence the produce 

 that might possibly be raised could be conveniently shipped, will 

 deter any settlers from seeking a home there until other more 

 favourable spots are occupied. There is no other instance with 

 which Captain Wharton is acquainted of an island of this height 

 retaining its coral covering so intact. Coral reefs have been 

 found at heights of 1000 feet in Cuba, in the Fiji Islands, and 

 other places ; but in all cases they are mere fragments, and the 

 intervening spaces sho v no signs of coral. Further and closer 

 investigation may record more direct evidence of its structure, 

 and of the successive steps which have resulted in its pre ent 

 condition ; but the Hydrographer thought our present knowledge 

 of Christmas Island was sufficient to make this short notice 

 interesting to the Society. 



